Summary

Platelet-rich plasma (PRP) has been used to promote periodontal regeneration following the premise that constituent transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor-AB will stimulate cell proliferation at the site of application. In previous studies, we demonstrated that PRP mimics TGF-β1 to modulate proliferation in a cell type-specific manner, that fibrin clot formation by PRP upregulates type I collagen, and that an unidentified factor(s) in PRP increases alkaline phosphatase (ALP) activity in human periodontal ligament (PDL) cell cultures. We have now examined the effects of PRP on in vitro mineralization. Platelet-rich plasma and PDL cells were prepared from human adult volunteers or rats. After 20 d of continuous treatment with PRP in dexamethazone (Dex)-containing osteogenic medium, PRP time dependently promoted mineralization by rat PDL cells but failed to fully induce the osteoblastic phenotype. Furthermore, when human PDL cells were induced to increase ALP activity in osteogenic medium that lacked Dex, a condition that should delay (or suppress) osteoblastic differentiation, transmission electron microscopy revealed that mineralized spicules were initially deposited onto PRP-derived platelet aggregates. Taken together with our previous data, these findings suggest that PRP provides platelet aggregates as nuclei to initiate mineralization while stimulating PDL cell proliferation, differentiation, and collagen production. The combination of these effects may effectively mediate PRP's ability to promote regeneration of periodontal tissue, including skeletal tissue, at the site of injury.

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Authors and Affiliations

Tomoyuki Kawase

1

Kazuhiro Okuda

2

Yoshinori Saito

2

Norio Amizuka

3

Hironobu Suzuki

4

Hiromasa Yoshie

2

1.Division of Cellular Pharmacology, Department of Signal Transduction Research, Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Graduate School of Medical and Dental SciencesNiigata UniversityNiigataJapan

2.Division of Periodontology, Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Graduate School of Medical and Dental SciencesNiigata UniversityNiigataJapan

3.Division of Oral Anatomy, Division of Anatomy and Cell Biology of the Hard Tissue, Graduate School of Medical and Dental SciencesNiigata UniversityNiigataJapan

4.Department of Oral Biological Science, Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Graduate School of Medical and Dental SciencesNiigata UniversityNiigataJapan